Control switch



A. W. SHEPHERD CONTROL SWITCH Nov. 8, 1938.

Filed Aug. 16, 1935 AV/JOV/ 3 Sheets-Sheet 2 fly wwmmem Nov. 8, 1938. A.w. SHEPHERD 2,136,220

CONTROL SWITCH Filed Aug. 16; 1955 5 Sheets-Sheet 3 Patented Nov. 8,1938 cago, Ill., a corporation of Illinois, and one-half to Everett N.McDonnell, Chicago, Ill.'

Application August 16, 1935, Serial Nb. 86,447

' 1 Claim. (c1. zoo-s4) This invention relates to control switches, and

is directed more particularly to control switches for controlling thelevel of 'water in boilers of steam heating systems and the like,although the 5 underlying principles of construction and operation ofthe present control switch are not limited to this particular field, butmay be employed to provide a control switch mechanism wherever afloat-controlled switching device is found necessary or desirable.

In its preferred embodiment, the present inven- 7 tion provides a devicewhich is intended to operate a switch when the water level in a boileror the like reaches a certain maximum, and with a cermm differential isadapted to operate the switch in the reverse manner when the level dropsa predetermined amount.

The switch of the present invention is housed entirely within a floatmember disposed for movement by the liquid, and is responsive tomovement of the float in'response to variations in level of the liquidfor closing and an electric circuit. The circuit controlled by'theswitchmay be connected to actuate acontrol valve for admitting '25 more waterto a boiler or the like, or it may be connected to operate a suitable.pumpor to stop the burner incase of low water orto do'both. It mayoperate any other deslredgiifeating mechanism or in combination with a)suitable alarm it 3p may be used to indicate high or low liquid level ina tank or boiler.

The float of the present invention is preferably a light weight'hollowclosed cylinder formed of sheet metal or the like, and provided withsuitable 35 means for supporting the switch in predetermined positionwithin the interior thereof. The float is supported in the liquid thelevel of which is to be controlled, by a flexible supporting meanscapable of allowing the float to move in accordo ance with variationsin'the liquid level, but which at the same time serves as a flexibleseal for closing the end of the float through which the conductors,leading to the switch contacts within the float, are led out forconnection to the con-;

,5 trol circuit. v I Another feature of the present invention is theprovision of a control switch disposed within the float, the float beingmounted for movement on a flexible sealing bellows whereby no lever armsor 0" actuating means need be connected to the float to secure operationof a remotely disposed switch corresponding to the movement of thefloat, which is a serious objection to the present type of float controlswitches with which I am familiar. This 5 eliminates the need of packingcr sealing means for lever arms or other elements and produces operationof the switch as a direct result of movement of the float, andconjointly therewith.

Another advantage possessed by the present invention is the provision ofa terminal plate '5 carried directly by' the. casing but sealed from theliquid within the casing,'which plate receives the conductors from theswitch within the float, through the flexible sealing means which formsa pivotal support for movement of the float in 10'- response tovariations of liquid level.

It is also an object of the present invention to provide resilientsupporting means for the switch casing within the float, which iscapable of frictionally holding the switch casing in flxed'posi- 15'tion within the float,and can readily be assembled and adjusted inposition within the interior of the float.

' -A still further object of the present invention is the provision of acontrol switch construction '20 formed in a large degree of metalstampings which can be readily assembled and easily secured in relativeposition to provide a float-controlled switch of the type disclosed. v pa r The present invention also lends itself to a construction'whereinthe switch may be directly supported in the wall of a boiler or thelike, with the float disposed in contact with the water in the boiler,and directly responsive to the level thereof, while the switch leads andcontrol circult is led outwardly of the open end of the float support toany desired device to be controlled.

A still further feature of the present invention resides in the mannerin which the control switch or low water cut-ofi housing may besupported with respect to the gage glass of the boiler, and connectedinto the liquid system of the boiler by a quick hook-up arrangement. c

Other objects and advantages of the present invention will appear morefully from the following detailed description, which, taken inconjunction with the accompanying drawings, will disclose to thoseskilled in the art the particular.

construction and operation of a preferred form of the present invention.

In the drawings: Figure 1 is a diagrammatic view on a reduced 'scaleillustratingone manner in which the control switch of the presentinvention maybe connected to a steam heating system or the like;

1 Figure 2 isa sectional view on an enlarged scale, taken through thecontrol switch casing and associated mechanism;

Figure 3 is a sectionalview through the float,

disposed in one of the offset pockets 85 of the switch housing, with asuitable body of mercury disposed therein, whereby upon a change inangularity of the switch the mercury moves from one pocket to the otherpocket, thereby bridging across the switch contacts or electrodes, oropening the circuit therebetween, depending upon the position of theelectrodes with respect to the pockets. The dividing hump between thepockets controls the diiferential within which the switch will operate.

The switch is supported within the cylinder 49 by means of a pair ofspring clip members 66, shown in detail in Figure 3, which are providedwith flattened base portions 51 riveted or otherwise suitably secured toa supporting strip 88, as by means of rivets 89. The supporting strip 68extends longitudinally of the cylinder49 and adjacent each end thereofis provided with downwardly ofiset leg portions 10 terminating insuitably curved frictionally engaging finger pieces 12 which are adaptedto engage the inner surface of the cylinder 49 for frictionally holdingthe switch casing 58 in flxed position therein. Two sets oi? springfingers are provided, normally urged outwardly against the inner surfaceof the cylinder 49 for holding the clip members 66 in position such thatthe switch housing 58 is disposed substantially centrally of thecylinder 49 and at any desired position with respect tothe ends of thecylinder.

In the operation of the control switch disclosed herein, liquid from theboiler or other device in which the liquid level is. to be controlledenters the casing I6 through the inlet opening l8, and since the floatcylinder 49 is hollow, it floats, due to the flexibility of the bellows44, upon the surface of the liquid, assuming, when the liquid is up tothe level indicated at I3, a substantially horizontally extendingposition, in which position the switch casing 58 is also supported bymeans of the spring clips engaging the same. As the level within thecasing l5 lowers, the float cylinder 49 tends to lower, as shown indotted line in Figure 2, and

the float tends to rotate about a point substantially intermediate theends of the flexible bellows 44, since the bellows are not of sufficientI strength to support the weight of the float and switch housing whenthe float is, not disposed in and subject to the buoyant effect of aliquid.

When the cylinder 49 assumes a position such that the radially flangedportion 56 of the ring 55 engages the upper surface of the web 51, theswitch casing 58 will be inclinedat such an angle with respect to thehorizontal as to produce actuation of the switch operating meansenclosed therein, thereby controlling the circuit extending through theconductors 22 and 23. For example, if desired the circuitmay bemaintained opened as long as the switch is maintained within the floatin the position shown in Figure 2. Upon dropping of the float due to thelowering of the liquid level, therefore, the mercury flows into positionsuch as to bridge between the switch contacts forclosing the circuit,whereby the valve 8 will be opened to allow for inflow of liquid to theboiler 5, whereby a portion of this liquid will flow through the outletat the lower end of the gauge glass into the port I8 of the casing Hi toraise the float to a position such that the circuit is again broken; atwhich time the valve 8 will be closed to prevent further flow of liquidinto the boiler.

If desired, the circuit may be arranged in the opposite manner, that is,with the float in the position shown in Figure 2, the circuit may beclosed to maintain the valve 8 in closed position, whereby upon loweringof the float and pivoting of the same about the bellows to increase theangularity of the switch casing, the switch is opened to provide forrelease of the closing bias upon the valve 8, whereby the valve 8 willbe opened by water pressure from the conduit 9 to produce a flow ofliquid into the boiler 5 suflicient to raise the float to its positionas shown in Figure 2L ,Obviously any desired circuit connections andoperationsmaybe produced by the ope'ration of the float controlledswitch, and in place of the valve 8 a pump, burner motor or othermechanism may well be substituted without departing from the underlyingprinciples of the present invention.

As shown in detail in Figures 5 and 6, I may provide a quick hook-uparrangement for attaching the housing of the control switch to anydesired boiler construction. Thus, in connection with a boiler, such asthe boiler 15, I provide bosses 18 in thewall thereof suitably tapped toreceive the horizontallyextending pipes l1 and 18 normally extending tovalves 19 and 80, respectively, of a gauge glass 82. Interposed betweenthe valves 19 and 80 and the pipes 1'! and 18 are a pair of Tconnections 83 and 84, having the intermediate portion thereof extendingin a horizontal direction rearwardly of the pipes 11 and 18, as shown inFigure 6.

The upper T connection is adapted to receive a fitting 85 connected to acurved pipe 86 extending downwardly through the quick hook-up connectionindicated generally at 81 into the top port 28 of the control switchhousing I 6. The lower port I! of thishousing has connected thereto adrain valve indicated generally at.88.

The horizontally extending port l8 of the hous-' ing i6 is provided witha short nipple 89 connecting the same to the T connection 84, wherebythe housing I6 is connected at its top to the T connection 83 and at itslower end to the T conection 84, and is disposed intermediate thevertical extent of the gaugeglass 82, whereby it is responsive to waterlevels within the range shown by the gauge glass- In order toaccommodate the housing It to any installation, I provide the quickhook-up connection 81 whereby the vertical extent of the gauge glass canbe of various lengths and yet the housing can be coupled into theconnection as shown. Thus there is provided the bushing 90, threadedinto the vertically extending port 20 of the housing I6, and providedwith a cylindricalinner surface adapted to receive the downwardlyextending end of the pipe 86. The bushing is provided intermediate itsends with a polygonal surface adapted to be engaged by a suitable wrenchfor tightening the same into the "threaded socket 28. The upper end ofthe bushing 90 is threaded to receive a packing gland nut 92 threadingthereover and engaging about the pipe 86. The nut 92 is recessed toreceive packing 93 which, upon tightening of the nut downwardly on thebushing, is adapted to compress the packing therebetween for sealing theexternal surface of the pipe 86. It is obvious that the pipe may beclamped in any desired vertical position with respect to the bushing 90in this manner to accommodate various spacing of the T connections 83and 84.

In Figure 4 I have disclosed a modified type of control switch which isadapted to be threaded directly into the side wall of a boiler, with thefloat subject to the level of the water in the boiler itself, and theswitch terminals and leads disposed in position outwardly of the boilerwall.

This construction comprises a nipple member 90, which is provided withexternal threads 90 adapted to thread into a suitably tapped opening ina boiler wall 01. A suitable inwardly projecting sheet metal sleeve issecured to the nipple 95, as by welding, soldering or the like, and isprovided with a stiflening flange 00 at its free end. The sleeve 00serves as a protection for the hollow light-weight metallic float memberI00,

which has its outer end I02 sealed to one end of a flexible sealingbellows I03 extending centrally through the nipple 90 and supported onthe annular plate I04, as indicated at I05. A suitable annular gasketI00 is interposed between the plate I04 and the outer face I01 of thenipple 00.

Secured to the face I01 0! the nipple 00 is a switch housing member I08,having an annular channel-shaped flange I00 receiving spaced bolts IIOfor securing it to the nipple 00 over the plate I04. At the open side ofthe member I00 is pro vided an insulating disc I I2 which, together withthe disc II3 provides a support for a pair of switch terminals II4supported therein. The terminals I I4 are connected through flexibleleads I i5 to the-glass envelope type mercury switch I I0 supported bysuitable brackets IIO within the float I00, in a manner similar to thatdescribed in'connection with Figure 1.

Terminal lugs II9 are supported on the outer end of the terminals H4 andreceive suitable terminal screws I20 for clamping conductors thereto toextend a control circuit through the switch IIO. An outlet boxcomprising the member I22 secured to the face I01 of nipple 00 bylaterally disposed screws, and having the outwardly and verticallyextending portion I23 forming a boxlike enclosure, is adapted to receivethe cable .which leads the circuit conductors to the terminal screws.

It is to be understood that the nipple 00 can be threaded to any desiredaxial length, so that it need not be threaded into the boiler wall todispose the shield 98 entirely within the boiler in cases where theinternal construction of the boiler does not permit such an arrangement.

In Figure 7 I provide a modifled control switch mounting which is shownonly diagrammatically, comprising a float housing I20, a float I20therein, and sealed to the flexible bellows I21, which is secured to asupporting plate I20 clamped between the outer face of the housing andan annular clamping plate .I29, whereby the interior of the float andbellows is sealed with respect to the interior of the housing I20. Theinterior of the float and bellows is sealed by a closure member I29secured to the open face of the housing and preventing escape of liquidwhich might leak through the float or bellows.

At its unsupported end the float I20 has rigidly supported therein anarm member I30, as indicated at I32. Intermediate its ends the float isprovided. with an internal stiflening spider I33 providing a secondsupport I34 for the arm I30. At its outer unsupported end the arm I30provides a support for a mercury switch member I20, which member isthereby made responsive to movement 01' the float I20 to control acircuit in any desired manner. The switch, as well as its connections,is sealed from the interior of the housing I20 by the plate I20, bellowsI21 and This modlfled construction can be adapted to I either the typeof housing shown in Figure l, or that shown in Figure 4, in which thehousing is directly supported in the boiler wall.

In Figures 8 and 9 I provide a control switch especially adapted forliquid fuel tanks and the like, although it may obviously also beemployed in the same manner as described in connection with thecontrol-switches shown in Figures 2 and 4.

The switch or float housing I 40 is provided with ports I42 and I43,whereby the housing may be connected at any desired level with the tank.The housing is provided with a closure disc I44, clamped between gasketsI40, which disc at its center supports the projecting flexible bellowsI40. The opposite end of the bellows carries a float I41 sealed thereto,whereby the interior of the float and bellows are sealed with respect tothe interior of the housing I40 A suitable stop I40 limits loweringmovement of the float I41.

Mounted within the float I41 is a suitable bracket member I 40, similarto the bracket 00 of Figure 2, which supports the three electrodemercury switch I00 within the float, the switch and its circuits beingshown in detail in Figure 10. The leads I02 for the switch are ledoutwardly through the bellows I 40 to a terminal plate I03, preferablyformed of insulating material. This plate I03v is clamped to the end ofthe housing I40 over the outermost gasket I40 by means of an annularchannel-shaped ring I04 and screws I00.

Each of the leads in is connected to a terminal bushing I00 as shown atI01, the bushings I00 comprising tubular rivets securing terminal lugsI00 in position on the outer face of the plate I03. The terminal lugsI00 are provided with terminal screws I00 for securing outgoingconductors thereto. The terminal plate is enclosed within a suitableoutlet box I00 having a peripheral flange I02 secured to the housing I40by screws I03.

This provides a sealed enclosure within the float, flexible bellows andthe terminal plate I03, in which the switch and its terminal connectionsare mounted. It sometimes occurs that a leak in the float I41 or in theflexible bellows develops. Where a device such as is here disclosed isemployed in connection with a tank oi oil, such leak, even though small,might become a serious matter. The seal provided by the plate I03prevents the escape'oi fluid and constitutes an important feature ofthis construction.

As shown in Figure 10, the switch I00 is provided with three electrodesI00, I00 and I01, having outgoing leads I00, I09 and I10, respectively.A suitable body oi mercury I12 is carried within the switch and acts asa contactor between the various electrodes.

The electrode I00 is connected to a suitable source of current throughlead I00 and conductor I13, and in the normal position of the float acircuit is completedthrough electrode I00, mercury alarm device I10. Thealarm device is therefore energized, indicating that the fuel level inthe supply tank is below a predetermined point. If the level is notraised, the burner will still continue to operate for a certain periodof time, and the float 1 will drop lower. At a predetermined point, themercury I12 will move away iromelectrode I81, breaking the burner motorcircuit, but still maintaining the alarm circuit. Obviously in place orthe alarm circuit a valve might be actuated to switch from the low fuelsupply tank to a reserve tank, 11' so desired.

By thismeans I prevent immediate shutting oil of the heating mechanismwhen the alarm device is actuated, to prevent inconvenience or possibledamage in, cold weather, but provide for shutting of! the burner whenthe level becomes,

dangerously low. The time interval between the actuation of the alarmcircuit and shutting oil of the burner is determined by the spacing ofthe electrodes within the switch and the rate at which fuel is fed fromthe tank to the burner.

It is therefore believed apparent that I have provided a control switchstructure capable of operation in instantaneous response to movement ofthe float, wherein a switch will be operated in a certain manner whenthe liquid level is at the desired maximum, and, with a certaindiirerential,

will function to produce reverse operation 01' the switch when theliquid -level has dropped a predetermined amount. The switch beingcontained within the hermetically sealed float, and having itsconductors extending through the sealing and flexing bellows, providesasimplified and eflicient structure whereby no motion of the float needbe transmitted-through sealing or packing means to a remotely disposedor externally positioned switch member.

Having described my invention in accordance with the patent statutes,what I claim as new and desire to secure by Letters Patent is:

' In a control device of the class described, a float member including asubstantially cylindrical body portion, a flexible bellows sealed to oneend of said body portion and extending axially outwardly therefrom, asubstantially cylindrical glass switch housing, spring clips forsupporting said housing, resilient supporting means secured to saidclips and engaging the inner periphery of said bodyportion to positionsaid housing substantially axially within said float member, and

flexible insulated conductors extending from said housing outwardlythrough said bellows.

mm w. swamp.

NW0 8, 1938 J. AUGIER ET AL ELECTRIC VALVE CONVERTING APPARATUS OriginalFiled June 28, 1935 5 Sheets-Sheet l Inventors?

